1. Field of the Invention
The present invention relates to a switching apparatus and an electronic apparatus, and more particularly to a switching apparatus for carrying out a switching operation with reduced noise and an electronic apparatus having the switching apparatus assembled therein and to be incorporated in an automotive vehicle.
2. Description of the Related Art
Up until now, there have been proposed a wide variety of conventional switching apparatuses available for an electric apparatus such as, for example, a DVD (Digital Versatile Disc) Video player, a CD (Compact Disc) Video player, a cassette tape player, a radio receiver, or the like, to be incorporated in an automotive vehicle for the purpose of simple in construction and inexpensive in production cost.
One typical example of the conventional switching apparatus 300 of this type is exemplified and shown in FIG. 5 as comprising a rear panel 350 and a front panel 310 spaced apart from the rear panel 350. The front panel 310 of the conventional switching apparatus 300 in part constitutes a front panel of an electronic apparatus to be mounted on an automotive vehicle, hereinlater simply referred to as “vehicle-mounted electronic apparatus”, not shown in FIG. 5. The front panel 310 has a first surface 311 outwardly exposed and a second surface 312 in face-to-face relationship with the rear panel 350. The front panel 310 is formed with a through bore 313 having an outer open end flush with the first surface 311 and an inner open end flush with the second surface 312.
The conventional switching apparatus 300 further comprises a push button 320 and a switch device 330. The switch device 330 includes a stationary contact member 333 fixedly mounted on the rear panel 350, and a movable contact member 334 movable with respect to the stationary contact member 333 to assume two different positions including a switch-on position in which the movable contact member 334 is brought in contact with the stationary contact member 333 to establish electrical connection between the movable contact member 334 and the stationary contact member 333 and a switch-off position in which the movable contact member 334 is brought out of contact with the stationary contact member 333 to establish electrical disconnection between the movable contact member 334 and the stationary contact member 333.
The push button 320 has a pushed portion 323. The pushed portion 323 of the push button 320 has a center axis extending substantially in perpendicular relationship with the first surface 311 and the second surface 312 of the front panel 310 and received in the through bore 313 of the front panel 310 to be reciprocatable along the center axis of the pushed portion 323 together with the movable contact member 334. The push button 320 is adapted to support the movable contact member 334 of the switch device 330 to be reciprocable to ensure that the movable contact member 334 is brought into and out of contact with the stationary contact member 333.
The push button 320 includes a horn projection 322 having a center axis, and pivotably engaged with the front panel 310 on the second surface 312. This means that the push button 320 is pivotably supported on the front panel 310 with the horn projection 322 around the center axis of the horn projection 322 to have the pushed portion 323 of the push button 320 reciprocated along the center axis of the pushed portion 323 to assume two different positions including a projected position in which the pushed portion 323 is projected outwardly of the outer open end of the through bore 313 to have the movable contact member 334 move with respect to the stationary contact member 333 toward the switch-off position and a retracted position in which the pushed portion 323 is in part retracted into the through bore 313 to have the movable contact member 334 move with respect to the stationary contact member 333 toward the switch-on position. The switch device 330 further includes a resilient member, not shown in FIG. 5, for resiliently urging the movable contact member 334 to have the movable contact member 334 move with respect to the stationary contact member 333 toward the switch-off position. The movable contact member 334 of the switch device 330 is opposing to and held in contact with the pushed portion 323 of the push button 320. The rattling of the push button 320 causes constituent elements forming part of the conventional switching apparatus 300 to generate a noise, hereinlater referred to as a “rattling noise”. The resilient member of the switch device 330 is operative to resiliently urge the pushed portion 323 of the push button 320 to have the pushed portion 323 of the push button 320 stationary held in the projected position, thereby preventing the push button 320 from being rattled especially when an external vibration is imparted to the conventional switching apparatus 300. This leads to the fact that the resilient member of the switch device 330 serves as means to prevent the push button 320 from generating the rattling noise.
The conventional switching apparatus 300 as previously mentioned, however, encounters a drawback that the push button 320 can be held in contact with the movable contact member 334 when the pushed portion 323 of the push button 320 is reciprocatable along the center axis of the pushed portion 323 with a long stroke of, for example, 0.7 mm, 1.0 mm, or more while, on the other hand, the push button 320 cannot be held in contact with the movable contact member 334 when the pushed portion 323 of the push button 320 is reciprocatable along the center axis of the pushed portion 323 with a short stroke of approximately 0.2 mm or less. This leads to the fact that the resilient member of the switch device 330 cannot resiliently urge the pushed portion 323 of the push button 320 to have the pushed portion 323 of the push button 320 stationary held in the projected position, thereby unable to prevent the push button 320 from being rattled as well as prevent the “rattling noise” from occurring when the pushed portion 323 of the push button 320 is reciprocatable along the center axis of the pushed portion 323 with a short stroke of approximately 0.2 mm or less.